Anemia After Trauma

Anemia is frequent among brain-injured patients, where it has been associated with an increased risk of poor outcome. The pathophysiology of anemia in this patient population remains multifactorial; moreover, whether anemia merely reflects a higher severity of the underlying disease or is a significant determinant of the neurological recovery of such patients remains unclear. Moreover, anemia is associated with reduced blood viscosity, which promotes venous return and decreases the resistance to systemic flow as well as reduces endothelial shear stress, resulting in an improved microvascular perfusion. Some of these brain-injured patients may develop hemodynamic instability or acute heart failure, which would significantly impair the compensatory increase in cardiac output to provide adequate cerebral oxygenation during anemia. Several studies have shown an association between anemia and poor outcome after TBI. Anemia has also been associated with changes in brain metabolism or oxygenation. 1.

Now, researchers have found evidence that anemia can negatively influence the outcomes of patients with traumatic brain injuries. Anemia occurs when there is a shortage of red blood cells, which causes reduced oxygen flow to vital organs throughout the body. Red blood cells contain hemoglobin, a protein crucial to the delivery of oxygenated blood. The researchers compared hemoglobin levels of these patients and their outcomes within one year of surgery. Despite also having more severe head and systemic injuries, patients with lower levels of hemoglobin had a poor outcome. For each increase in hemoglobin of 1 gram above 7 grams per deciliter of blood, the likelihood of a good outcome increased by 33 percent. 2

There has been a lack of consensus among physicians regarding the relationship of anemia and traumatic brain injuries on a patient’s health. Because of this uncertainty, treatment protocols are unclear and inconsistent. An observational study found that a patient’s outcome is worse when he or she is anemic 3

“When people with traumatic brain injuries arrive at the hospital, they often have other injuries that can cause a lot of blood loss. The drop in blood pressure caused by the blood loss and the decreased amount of hemoglobin in the blood can reduce the flow of oxygen to the brain,” said Dr. Claudia Robertson, professor of neurosurgery at Baylor and medical director of the Neurosurgical Intensive Care Unit at Harris Health Ben Taub. “These are two issues that we must deal with in the early management of patients with traumatic brain injury.